昆虫拒食剂和天然杀虫剂是植物化学防御成分的重要类型。楝科植物中特征成分四降三萜是植物杀虫剂和昆虫拒食剂的重要来源。在我们的前期研究中，楝科山楝属植物山楝枝叶的化学成分及其生物活性进行了系统的研究，得到新化合物20个（包括 18个四降三萜）。特别是我们发现aphanamixoid型新骨架四降三萜9个，并通过单晶衍射确定了aphanamixoid A（1）的绝对构型。最重要的是，发现该类型新颖骨架化合物具有显著昆虫拒食活性，对棉铃虫拒食活性的EC50值在0.008-0.049μmol/cm2之间。同时aphanamixoidA（1）对甜菜夜蛾也具有昆虫拒食活性，其EC50=0.052μmol/cm2，因此，值得进一步深入对山楝属中该类型骨架四降三萜进行系统的研究，阐明该类新骨架四降三萜的化学防御活性及其初步的构效关系，为开发新天然农药打下基础。

Inesect and antifeedent agents and natural pesticides are important chemical defense component for plants. Limonoids,the characteristic components of Meliaceae plants, are important source of insect antifeedent agents and natural pesticides. In our pervious research,20 new compounds including 18 new limonoids, were isolated from Aphanamixis polystachya (Meliaceae). Moreover, nine novel aphanamixoid type limonoids were identified, and the absolute configuration of aphanamixoid A (1) was determined by X-ray method. It is most important to find this type limonoids showed significant insect antifeedant activity against cotton bollowrom antifeedant activity,with EC50 values between 0.008-0.049 μmol/cm2. Thus, it is worth to further study SAR of this new skeleton limonoids for the development of new natural pesticides.